The present invention relates to wheel probes for insertion into the bore of a pipe for the purpose of ultrasonically inspecting the wall of the pipe.
Known forms of such wheel probes usually comprise a hollow wheel assembly having a soft deformable or inflatable tire around its outer circumference, and ultrasonic transducers located within the wheel assembly for directing and receiving ultrasonic energy through the tire which is urged into contact with the internal surface of the pipe. An acoustic coupling fluid is provided between the tire and the pipe surface to provide transmission of the ultrasonic energy.
It has been found that existing wheel probes are unsatisfactory for certain kinds of applications with which the present invention is particularly concerned, namely, the non-destructive testing of gas or other pipelines in which the wheel probes are carried on an inspection vehicle which is propelled at high speed by the fluid flow in the pipeline, and which encounters obstructions such as weld rings or branch pipe openings likely to cause damage to the wheel probes. Furthermore, it is essential in such applications that adequate acoustic coupling is maintained between the relative moving parts of the wheel probe, and that the outer rim of the wheel is correctly aligned relative to the internal surface of the pipe.